JP2003253017A - Polyester film for metallic plate lamination fabrication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a polyester film for metallic plate lamination fabrication which improves resistance to hydrolysis, particularly taste and flavor preservation while maintaining heat resistance, impact resistance, deep drawing properties, and rust preventive properties, is inexpensive and hygienically desirable. <P>SOLUTION: This film is composed of a biaxially oriented polyester film having ethylene terephthalate as the major repeating unit. The polyester contains a phosphorus compound and a titanium compound soluble in the polymer. The phosphorus compound is a phosphonate compound represented by the formula (I): R<SP>1</SP>OC(O)XP(O)(OR<SP>2</SP>)<SB>2</SB>(wherein R<SP>1</SP>and R<SP>2</SP>are each a 1-4C alkyl group; X is CH<SB>2</SB>or CH(Y); Y is benzene ring; and R<SP>1</SP>and R<SP>2</SP>may be the same or different). Simultaneously, the film contains 0.05-5 wt.% inert particles having an average particle diameter of ≤2.5 μm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester film for laminating and processing metal plates. More specifically, it shows excellent moldability when it is attached to a metal plate and used for can manufacturing such as drawing, and it has excellent heat resistance, retort resistance, flavor retention, impact resistance, rust resistance, etc. And a polyester for laminating and forming metal plates capable of producing metal cans such as beverage cans and food cans.

[0002]

2. Description of the Related Art Metal cans are generally coated to prevent corrosion on the inside and outside, but recently, for the purpose of simplifying the process, improving hygiene, and preventing pollution, rust prevention without using organic solvents. The development of a method for obtaining the property has been advanced, and as one of them, coating with a thermoplastic resin film has been attempted. That is, a method of making a can by laminating a thermoplastic resin film on a metal plate such as tin plate, tin-free steel, aluminum or the like and then making a can is under study. Polyolefin films and polyamide films have been tried as this thermoplastic resin film, but they do not satisfy all of the molding processability, heat resistance, impact resistance, and flavor and aroma retention.

Therefore, a polyester film, particularly a polyethylene terephthalate film, has attracted attention because of its well-balanced characteristics, and several proposals based on this have been made (JP-A-56-10451). Japanese Patent Laid-Open No. 64-22530, Japanese Patent Laid-Open No. 1-19
No. 2545, JP-A-1-192546, JP-A-2-57339 and the like).

[0004]

However, the molding processability,
Satisfaction with all of retort resistance, flavor retention, and aroma retention may be insufficient, especially in the case of molding that involves large deformation.

For example, Japanese Patent Laid-Open No. 5-339348,
JP-A-6-39979 discloses that a metal plate having a specific melting point, a glass transition temperature or a specific terminal carboxyl group concentration is provided as a material satisfying molding processability, heat resistance, impact resistance and flavor retention. A polyester film for a combined molding process has been proposed. However, when a can using these films is used in, for example, a beverage container, depending on the type of the beverage, a change in odor or taste as described in JP-A-55-23136 can be detected. Has been pointed out.

Further, Japanese Patent Laid-Open No. 6-116376 proposes a polyester film for metal plate forming, which comprises a copolyester containing a specific amount of an alkali metal element and a germanium element. However, when this film is used, it exhibits excellent flavor retention and aroma in a process such as a cold pack system in which heat is not applied at the stage of filling contents, but heat treatment is performed at the stage of filling contents such as retort treatment. In the known process, there is a problem that sufficient flavor and aroma retention cannot be obtained.

Further, JP-A-9-241361 and JP-A-10-231413 propose a copolyester in which the content of the alkali metal and the catalyst metal compound and the compounding ratio of the phosphorus compound are within a specific range. .
However, even if these films are used, they are not always sufficient in terms of the productivity of polyester and the heat deterioration during production of a biaxially oriented film, and further improvement in performance has been desired.

Furthermore, JP-A-9-70934 proposes a laminated polyester film containing a specific amount of a specific metal. However, in a process such as a retort process in which heat treatment is performed at the stage of filling contents, there is a problem that hydrolysis resistance is not sufficient and sufficient flavor and aroma retention cannot be obtained.

The present invention solves the above problems and, while retaining the excellent heat resistance, impact resistance, deep drawing formability and rust resistance of conventional polyester films, it has hydrolysis resistance, especially taste retention. An object of the present invention is to obtain a polyester film for metal plate laminating and forming, which has improved aroma retention and is inexpensive and desirable in hygiene.

[0010]

Means for Solving the Problems A polyester film for laminating and forming metal plates of the present invention is a polyester film for laminating and forming metal plates, which comprises a biaxially oriented polyester film containing ethylene terephthalate as a main repeating unit. A phosphorus compound and a titanium compound soluble in the polymer are contained therein, the phosphorus compound is a phosphonate compound represented by the following formula (I), and the film has an average particle diameter of 2.5 μm or less and is inactive. It is characterized by containing 0.05 to 5% by weight of particles. The present invention with such a constitution has a remarkable effect in improving hydrolysis resistance and flavor retention. R ¹ OC (O) XP (O) (OR ² ) ₂ (I) In the formula (I), R ¹ and R ² have 1 to 4 carbon atoms.
An alkyl group of X is —CH ₂ — or —CH (Y) —
(Y represents a benzene ring), and R ¹ and R ² may be the same or different.

Generally, as a polycondensation reaction catalyst for polyesters, antimony compounds, germanium compounds and the like are used, but in order to exhibit the excellent hydrolysis resistance and flavor and aroma retention in the present invention, a polymer is used. It is necessary to use soluble titanium compounds.

Examples of the titanium compound include titanium acetate and titanium tetrabutoxide (TBT), and the following general formula (II) is particularly preferable in order to obtain a balance between flavor retention and heat resistance. Or a compound represented by the general formula (II) and the following general formula (I
It is a product obtained by previously reacting with an aromatic polycarboxylic acid represented by II) or an anhydride thereof. Ti (OR ³ ) ₄ (II) Here, R ³ in the formula (II) is an alkyl group or a phenyl group.

[0013]

[Chemical 2]

Here, n in the formula (III) is an integer of 2 to 4.

The titanium tetraalkoxide represented by the general formula (II) is not particularly limited as long as R ³ is an alkyl group and / or a phenyl group, but titanium tetraisopropoxide, titanium tetrapropoxide, titanium tetraalkoxide. Butoxide, titanium tetraethoxide, titanium tetraphenoxide and the like are preferably used. Further, the compound represented by the general formula (II
As the aromatic polycarboxylic acid represented by I) or its anhydride, phthalic acid, trimellitic acid, hemimellitic acid, pyromellitic acid and their anhydrides are preferably used. In the case of reacting the titanium compound with an aromatic polyvalent carboxylic acid or an anhydride thereof, a part of the aromatic polyvalent carboxylic acid or an anhydride thereof is dissolved in a solvent, and a titanium compound is added dropwise thereto, 30 at a temperature of 0-200 ° C
Let it react for more than a minute.

Further, a polyester may be added with a heat stabilizer inhibitor and an antioxidant for the purpose of suppressing heat deterioration during polymer melt polymerization and molding processing. To develop heat resistance and heat resistance,
The compound represented by the above general formula (I) is used.

The phosphonate compound represented by the general formula (I) includes carbomethoxymethanephosphonic acid, carboethoxymethanephosphonic acid, carbopropoxymethanephosphonic acid, carboptoxymethanephosphonic acid, carbomethoxy-phosphono-phenylacetic acid, Carboethoxy-phosphono-phenylacetic acid, carboprotoxy-phosphono-phenylacetic acid and carbobutoxy-phosphono-phenylacetic acid dimethyl ester, diethyl ester, dipropyl ester and dibutyl ester, tetraethyl-phosphonoacetic acid, tetramethyl-phosphonoacetic acid. However, these may be used alone or in a mixture.

The polyester of the present invention is not particularly limited depending on its production method, but the above-mentioned titanium compound as a catalyst and phosphorus compound as a stabilizer are represented by the following formulas (1) to (3).
It is preferable to satisfy And more preferably, it is a range of the following formulas (4) to (6). 2 ≦ Ti ≦ 10 (1) 0.1 ≦ P / Ti ≦ 10 (2) 5 ≦ Ti + P ≦ 40 (3) 4 ≦ Ti ≦ 8 (4) 0. 4 ≦ P / Ti ≦ 6 (5) 8 ≦ Ti + P ≦ 30 (6) In the above formula, Ti is the titanium element concentration (mmol%) of the polyester-soluble titanium compound contained in the polyester. And P represents the phosphorus element concentration (mmol%) of the phosphorus compound contained in the polyester.

As in the above formula, it is preferable to contain 2 to 10 mmol% of a soluble titanium metal element in the polymer. It is particularly preferably in the range of 4 to 8 mmol%. When the titanium metal element is less than 2 mmol%, the productivity of the polyester is lowered and a polyester having a target molecular weight cannot be obtained. Further, the titanium metal element is 10 mmol%
On the other hand, if it exceeds the above range, the thermal stability is decreased, and the decrease in the molecular weight during the production of the film becomes large, so that the intended polyester cannot be obtained. Incidentally, the term “titanium metal element soluble in the polymer” as used herein means a titanium compound used as a transesterification reaction catalyst and a titanium compound used as a polycondensation reaction catalyst when a first-stage reaction by a transesterification reaction is performed. The total number of compounds is shown.

When P / Ti is less than 0.1, the thermal stability and the flavor and aroma retention are sharply lowered, which is not preferable. Further, when P / Ti exceeds 10, the polymerization reactivity of the polyester is significantly lowered, which is not preferable.

Further, if the content of (Ti + P) is less than 8 mmol%, the productivity in the film forming process by the electrostatic printing method is deteriorated and the uniformity of the film thickness is also deteriorated. Is deteriorated and the heat embrittlement is deteriorated, and satisfactory performance may not be obtained, which is not preferable. On the other hand, when (Ti + P) exceeds 30 mmol%, the flavor property is deteriorated due to the low molecular weight component of the polyester generated by the interaction with the polyester, and satisfactory performance may not be obtained, which is not preferable.

The polyester in the present invention is a polyester containing ethylene terephthalate as a main repeating unit. This polyester is preferably a copolymerized polyethylene terephthalate obtained by copolymerizing a third component other than the component constituting the ethylene terephthalate unit in terms of heat resistance and moldability. The third component (copolymerization component) may be either a dicarboxylic acid component or a glycol component.

The dicarboxylic acid component preferably used as the third component is an aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, isophthalic acid or phthalic acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid or the like. Examples thereof include aliphatic dicarboxylic acids such as, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and these can be used alone or in combination of two or more. Of these, 2,6-naphthalenedicarboxylic acid and isophthalic acid are preferred.

The glycol component preferably used as the third component is diethylene glycol, propylene glycol, neopentyl glycol, butanediol,
Examples thereof include aliphatic diols such as pentanediol and hexanediol, alicyclic diols such as cyclohexanedimethanol, aromatic diols such as bisphenol A, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. These may be used alone or in combination of two or more. Of these, diethylene glycol is preferred. The copolymerization amount of the diethylene glycol component with respect to the total glycol component is preferably 4 mol% or less, more preferably 2.5.
It is not more than mol%. If the copolymerization amount of diethylene glycol exceeds 5 mol%, the heat resistance may decrease. The diethylene glycol component also includes a diethylene glycol component that is a by-product when producing a copolymerized aromatic polyester having ethylene glycol as the glycol component.

The polyester of the present invention can be produced by any method. For example, a copolymerized polyethylene terephthalate copolymerizing a third component such as isophthalic acid will be described. A lower alkyl ester of terephthalic acid and isophthalic acid is transesterified with ethylene glycol, or terephthalic acid and isophthalic acid are mixed with ethylene glycol. And esterification reaction of terephthalic acid glycol ester and / or its low polymer with isophthalic acid to produce a terephthalic acid-isophthalic acid glycol ester and / or its low polymer. The first step reaction is carried out. This reaction product is heated in a high vacuum to allow the deglycolization reaction to proceed, whereby the polycondensation reaction is performed until the desired degree of polymerization is reached, whereby the target polyester can be obtained. The polyester obtained by the above method (melt polymerization) can be made into a polymer having a higher degree of polymerization by a polymerization method in a solid phase state (solid phase polymerization), if necessary.

In the present invention, when the first stage reaction at the time of melt polymerization is carried out by a transesterification reaction, it is necessary to add a transesterification reaction catalyst during the reaction. Generally, examples of the transesterification reaction catalyst include a calcium compound, a manganese compound, a titanium compound, and the like, and any of them can be used, but the amount of the catalyst can be minimized, and the obtained polyester has excellent flavor and aroma retention. Titanium compounds that are soluble in the polymer are preferred. Further, it is necessary to use a titanium compound soluble in the polymer as a catalyst used in the polycondensation reaction, in view of excellent hydrolysis resistance and flavor retention.

The intrinsic viscosity (ο-
Chlorophenol, 35 ° C) is preferably in the range of 0.50 to 0.80, and more preferably 0.55 to 0.7.
The range of 5, especially 0.60 to 0.70 is preferable. When the intrinsic viscosity is less than 0.50, the impact resistance of the film becomes insufficient, which is not preferable. On the other hand, if the intrinsic viscosity exceeds 0.80, it is necessary to excessively increase the intrinsic viscosity of the raw material polymer, resulting in poor productivity.

The glass transition temperature (hereinafter sometimes abbreviated as Tg) of the film of the present invention is 70 ° C. or higher, particularly 73 ° C.
The above is preferable. If the Tg is less than 70 ° C, the heat resistance tends to be poor, and the flavor and aroma retention property of the film after retort treatment may deteriorate. Here, the Tg of the film was determined by placing 20 mg of the sample in a DSC measuring pan, heating and melting on a 290 ° C. heating stage for 5 minutes, and then rapidly cooling and solidifying the sample pan on an aluminum foil laid on ice to obtain Du Pont. Instruments 910
According to the method of determining the glass transition point using DSC at a temperature rising rate of 20 ° C./min.

The melting point of the film of the present invention is 210-25.
It is preferably in the range of 0 ° C, particularly in the range of 215 to 245 ° C. If the melting point is less than 210 ° C., the heat resistance of the film is poor, which is not preferable. On the other hand, if the melting point exceeds 250 ° C., the crystallinity of the film is increased and the moldability of the film is impaired, which is not preferable. Here, the melting point of the film is measured by Du Pont Instruments.
910 DSC is used to determine the melting peak at a heating rate of 20 ° C./min. The sample amount is 20 mg.

Further, the polyester film in the present invention has a terminal carboxyl group concentration of 40 eq / 10 ⁶ g or less, particularly preferably 35 or less. The terminal carboxyl group is A. Conix's method (M
acromol. Chem. 26, 226 (19
58)).

The polyester as described above in the present invention must contain inert particles having an average particle diameter of 2.5 μm or less. The particles act as a lubricant. The average particle size is preferably 0.05 to 2.0 μm, more preferably 0.1 to 1.5 μm. The average particle size is 2.
If it exceeds 5 μm, pinholes are likely to be formed during molding, which is not preferable. Here, as the average particle diameter of the particles, the value at the cumulative 50% point in the equivalent spherical diameter distribution obtained by the centrifugal sedimentation type particle size distribution measuring device is used.

Further, the content of the inert particles used in the present invention needs to be 0.05 to 5.0% by weight. It is preferably 0.08 to 3.0% by weight, and more preferably 0.1 to 1.0% by weight. If the content is less than 0.05% by weight, the film winding property will be insufficient and the productivity will be poor. On the other hand, if it exceeds 5.0% by weight, pinholes are formed in the film during the molding process, which is not preferable.

The inert particles used in the present invention include colloidal silica, porous silica, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, zirconia, kaolin, and composite oxide particles as the inorganic particles. Examples of the organic particles include crosslinked polystyrene, acrylic crosslinked particles, methacrylic crosslinked particles, and silicone particles. Further, the particles are not limited to the externally added particles as described above, and for example, internally precipitated particles obtained by precipitating a part or all of the catalyst used in the production of the copolyester in the reaction step may be used. It is also possible to use externally added particles and internally precipitated particles in combination. Among these, inorganic particles are preferable, and colloidal silica is particularly preferable in terms of molding processing.

In the present invention, the method of incorporating such inert particles into the copolyester is not particularly limited, and examples thereof include a method of adding the inert particles at an arbitrary stage of the copolyester production process. In addition, additives such as an antioxidant, a heat stabilizer, a viscosity modifier, a plasticizer, a hue improver, a nucleating agent, and an ultraviolet absorber can be added to the copolyester, if necessary.

The film of the present invention is used in the form of a biaxially stretched film which is biaxially stretched and optionally heat set. The method of successive biaxial stretching will be specifically described below. In the film of the present invention, polyester is melted, extruded from a die, laminated and fused before solidification, and then rapidly cooled to obtain a substantially amorphous polyester sheet. Next, this sheet is heated by roll heating, infrared heating or the like and stretched in the longitudinal direction. At this time, the stretching temperature is preferably 20 to 40 ° C. higher than the glass transition point (Tg) of polyester, and the stretching ratio is preferably 2.7 to 3.6 times. Stretching in the transverse direction is preferably started at a temperature higher than Tg by 20 ° C. or more and while being heated to a temperature 100 to 130 ° C. lower than the melting point (Tm) of polyester. The transverse stretching ratio is 2.
It is preferably 8 to 3.7 times. The heat setting temperature is selected in the range of 150 ° C to 205 ° C to adjust the film quality according to the melting point of the polyester polymer.

In the present invention, the total amount of the alkali metal element, antimony element and germanium element contained in the polyester is 5 ppm by weight or less, preferably 3 weight p.
It must be pm or less. Further, the total amount of the antimony element and the germanium element is preferably less than 1 weight ppm. Here, the amount of alkali metal element is
P of Li, Na and K elements quantified by atomic absorption spectrometry
It is the sum of pm concentrations. The amount of antimony element and the amount of germanium element are quantified by fluorescent X-ray analysis. When the total amount of the alkali metal element, the antimony metal element and the germanium metal element exceeds 5 ppm by weight, the flavor retention and aroma retention property, particularly after the retort treatment, is deteriorated.

Since the polyester film of the present invention is particularly used for food cans or beverage cans, the less substance that elutes or scatters from the film, the better.
It is virtually impossible to eliminate those substances at all. Therefore, in order to use it for food cans or beverage cans, for example, the extraction amount per 1 cm ² of film when extracted with ion-exchanged water at 121 ° C. for 2 hours is preferably 10 μg or less, and 8 μg or less. Is more preferable. In order to reduce the amount of extraction, the kind and content of the catalyst compound and the stabilizer compound in the polyester film and the kind and amount of the copolymerization component may be optimized. When changing the type and amount of the copolymerization component, the glass transition temperature, melting point and crystallinity of the polyester film may be changed. Therefore, it is preferable to optimize the type and content of the catalyst compound and the stabilizer compound. .

A metal plate to which the film of the present invention is attached,
In particular, tin plates, tin-free steel plates, aluminum plates and the like are suitable as metal plates for can manufacturing. The film can be attached to the metal plate by, for example, the following methods (a) and (b).

(A) The metal plate is heated above the melting point of the film, the films are laminated and then cooled, and the surface layer part (thin layer part) of the film in contact with the metal plate is made amorphous and brought into close contact.

(B) An adhesive layer is pre-coated on the film with a primer, and this surface is bonded to a metal plate. As the adhesive layer, a known resin adhesive such as an epoxy adhesive, an epoxy-ester adhesive, an alkyd adhesive, or the like can be used.

[0041]

EXAMPLES The present invention will be further described below with reference to examples. The characteristics of the film were measured and evaluated by the following methods.

(1) Intrinsic viscosity of polyester ([η]) Measure in orthochlorophenol at 35 ° C.

(2) Melting point of polyester (Tm) Du Pont Instruments 910 D
According to a method of determining a melting peak at a heating rate of 20 ° C./min using SC. The sample amount is 20 mg.

(3) Glass transition temperature (Tg) 290 was put into a pan for DSC measurement and 290
After heating and melting for 5 minutes on a ℃ heating stage, the sample pan was rapidly cooled and solidified on an aluminum foil laid on ice, and then Du
Pont Instruments 910 DSC
Is used to determine the glass transition point at a temperature rising rate of 20 ° C./min.

(4) Lubricant average particle diameter The diameter with an integrated volume fraction of 50% in the equivalent spherical diameter distribution measured by a centrifugal sedimentation type particle size distribution measuring apparatus is taken as the average particle diameter.

(5) Amount of titanium metal element, germanium metal element, antimony metal element and phosphorus element amount The film sample is heated and melted at 240 ° C. to form a circular disk, and a catalyst is produced by using Rigaku fluorescent X-ray apparatus 3270 type. The metal element and phosphorus element concentrations were quantified.

(6) Diethylene glycol content The film was dissolved in a CDCl ₃ / CF ₃ COOD mixed solvent and measured by ¹ H-NMR.

(7) The hydrolysis-resistant film is dipped in a container filled with ion-exchanged water to 70
Hold at 30 ° C for 30 days. The decrease in molecular weight at this time was evaluated by measuring the intrinsic viscosity [η] described in (1). ◯: The decrease of [η] is 0.04 or less Δ: The decrease of [η] is more than 0.04 and less than 0.10 ×: The decrease of [η] is 0.10 or more

(8) The laminating film was laminated with a tin-free steel plate having a plate thickness of 0.25 mm which was heated to the melting point of the copolyester or more, and then cooled to obtain a coated steel plate. Observe this coated steel plate,
The laminating property was evaluated according to the following criteria.

(8A) Bubbles and Wrinkles Judgment Criteria (Lamination A) ◯: No bubbles or wrinkles are observed. B: Bubbles and wrinkles are seen in 2 to 3 places per 10 cm in length. X: Many bubbles and wrinkles are seen.

(8B) Criteria for determination of heat shrinkage (lamination B) ◯: Shrinkage is less than 2%. Δ: Shrinkage rate is 2% or more and less than 5%. X: Shrinkage rate is 5% or more.

(9) Deep drawing workability-1 A tin-free steel plate laminated with a film in the same manner as in the above (8) is cut into a disk shape having a diameter of 150 mm, and deep drawing is performed in four steps using a drawing die and a punch. It was processed to prepare a side-surface seamless container having a diameter of 55 mm (hereinafter, may be abbreviated as a can). The following observations were performed on this can, and the cans were evaluated according to the following criteria. ◯: No whitening or breakage is observed in the film processed without abnormality. Δ: Whitening is observed at the top of the film can. X: Film breakage is observed in a part of the film.

(10) Deep drawing workability-2 The cans obtained in (9) above were observed and tested as follows, and evaluated according to the following criteria. ◯: Processed without any abnormality, rust prevention test of film surface in can (1% NaCl aqueous solution was put in the can, electrodes were inserted, and the current value was measured when a voltage of 6 V was applied with the can body as an anode. In the following, it may be abbreviated as ERV test) and shows 0.1 mA or less. X: There is no abnormality in the film, but the current value exceeds 0.1 mA in the ERV test, and pinhole-like cracks originating from the coarse lubricant of the film are observed when the energized portion is enlarged and observed.

(11) Impact resistance With respect to cans having good deep drawing workability, after pouring water into the cans and cooling them to 0 ° C., 10 pieces each were dropped from a height of 30 cm onto the PVC tile floor surface, and then ERV. The test was conducted and evaluated according to the following criteria. Good: 0.2 mA or less for all 10 pieces. Δ: 0.2 mA was exceeded for 1 to 5 pieces. X: 0.2 mA was exceeded for 6 or more, or cracking of the film was already observed after dropping.

(12) Heat embrittlement resistance After the cans, which had good deep drawing workability, were heated and held at 200 ° C. for 5 minutes, the aforementioned impact resistance was evaluated and evaluated according to the following criteria. ◯: 0.1 mA or less for all 10 pieces. Δ: 0.1 to 5 was exceeded for 1 to 5 pieces. X: The value was 6 mA or more and exceeded 0.1 mA, or cracking of the film was already observed after heating at 200 ° C. for 5 minutes.

(13) Retort resistance With respect to a can having good deep drawing workability, water was fully poured, and retort treatment was performed at 120 ° C. for 1 hour in a steam sterilizer.
It was stored at 60 ° C for 60 days. 10 cans after processing, height 5
ERV in the can after dropping from 0 cm to the PVC tile floor
The test was conducted and evaluated according to the following criteria. ◯: 0.1 mA or less for all 10 pieces. Δ: 0.1 to 5 was exceeded for 1 to 5 pieces. ×: The value was over 0.1 mA for 6 or more, or cracks of the film were already observed after dropping.

(14) Flavor retention and aroma retention-1 A can having good deep drawability was filled with ion-exchanged water and stored at room temperature (20 ° C.) for 120 days. Using the filling liquid, a tasting test was conducted by 30 panelists and compared with ion-exchanged water for comparison, and evaluated according to the following criteria. ⊚: 3 or less out of 30 people felt a change in taste and aroma as compared with the comparative solution. ◯: 4 to 6 out of 30 people felt a change in taste and aroma as compared with the comparative solution. Δ: 7 to 9 out of 30 people felt a change in taste and aroma as compared with the comparative solution. X: 10 or more out of 30 people felt a change in taste and aroma as compared with the comparative liquid.

(15) Flavor-preserving and aroma-preserving property-2 A can having good deep drawing workability was filled with ion-exchanged water, retort-treated at 121 ° C. for 2 hours in a steam sterilizer, and then at room temperature (20 ° C.). ) Was stored for 120 days. Using the filling liquid, a tasting test was conducted by 30 panelists and compared with ion-exchanged water for comparison, and evaluated according to the following criteria. ⊚: 3 or less out of 30 people felt a change in taste and aroma as compared with the comparative solution. ◯: 4 to 6 out of 30 people felt a change in taste and aroma as compared with the comparative solution. Δ: 7 to 9 out of 30 people felt a change in taste and aroma as compared with the comparative solution. X: 10 or more out of 30 people felt a change in taste and aroma as compared with the comparative liquid.

[Examples 1 to 4 and Comparative Examples 1 to 9] Table 1
The acid component, the copolymerization component, the metal catalyst, and the phosphorus compound shown in 1 were used. In the symbols in Table 1, DMT in the acid component is dimethyl terephthalate, TA is terephthalic acid, IA in the copolymerization component is isophthalic acid, NDC is dimethyl 2,6-naphthalenedicarboxylate, and TE in the phosphorus compound.
PA is tetraethylphosphonoacetic acid, TMP is trimethyl phosphate, PA is orthophosphoric acid, Ti in the metal element is titanium element, Sb is antimony element, Ge is germanium element, P / Ti is phosphorus element and titanium remaining in the polyester. The concentration ratio with the element, Ti + P is the sum of the concentrations of the phosphorus element and the titanium element remaining in the polyester (the unit is mmol%), and DEG is diethylene glycol.

The copolymerized polyethylene terephthalate (average particle size 0.5 μm, containing 0.1% by weight of spherical silica particles) obtained so that the metal content in the film had the value shown in Table 1 was dried, It was melt extruded at 280 ° C. and rapidly solidified to obtain an unstretched film. Next, this unstretched film was stretched 3.0 times in the longitudinal direction at 110 ° C., then stretched 3.0 times in the transverse direction at 120 ° C. and heat-set at 180 ° C. to obtain a biaxially oriented film. The thickness of each obtained film is 25
was μm. The characteristics of the film are shown in Table 1, and the evaluation results are shown in Table 2.

The polycondensation catalyst TM described in Examples is used.
T was prepared by preparing TBT (tetrabutoxytitanium) and TMA (trimellitic acid) in the following manner. To an ethylene glycol solution of trimellitic anhydride (0.2%), ½ mol of tetrabutoxytitanium was added to trimellitic anhydride, and the mixture was kept at 80 ° C. under atmospheric pressure in air and reacted for 60 minutes. Then, the mixture was cooled to room temperature, the produced catalyst was recrystallized with 10 times the amount of acetone, the precipitate was filtered with filter paper, and dried at 100 ° C. for 2 hours to obtain the target catalyst.

As is clear from Table 2, a phosphonate compound was used as the phosphorus compound, and the polymer-soluble titanium compound was contained in the titanium element concentration in the range of 2 to 10 mmol%, and (P / Ti) and (Ti + P) were Although the film of the present invention in the proper range obtained good performance,
When a phosphoric acid compound is used (Comparative Examples 1, 2, 5),
When the melting point of the polyester is 210 ° C. or lower (Comparative Examples 3 and 4), when a catalyst metal other than a titanium compound is used (Comparative Examples 6 and 7), and when the phosphorus compound is out of the proper range (Comparative Example 8, In No. 9), deep drawability, impact resistance, and flavor retention were not good.

Further, the can using the film of the present invention is
The heat resistance, the deep-drawing processability, and the impact resistance were good, and in particular, the flavor retention and aroma resistance and the hydrolysis resistance were excellent.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

EFFECTS OF THE INVENTION According to the present invention, while maintaining excellent heat resistance, impact resistance, deep drawing formability, and rust resistance, hydrolysis resistance and flavor retention are improved, and it is inexpensive and hygienic. It is possible to provide a polyester film for metal plate laminating and forming, which is also desirable above.

Continued front page    F-term (reference) 4F071 AA46 AB26 AC05 AC15 AE22                       AF02 AF53 AH05 BC01 BC02                 4J002 CF061 CF081 DE138 DE148                       DE238 DG048 DH048 DJ018                       DJ038 EC077 EH147 EW126                       FD018 FD206 FD207 GF00                       GG01

Claims (8)

[Claims] 1. Mainly repeating ethylene terephthalate
Gold consisting of biaxially oriented polyester film
In the polyester film for metal plate laminating and forming,
Soluble in phosphorus compounds and polymers in polyester
Containing a titanium compound, wherein the phosphorus compound has the following formula (I)
A phosphonate compound represented by the formula
The average particle size of the particles is 0.05 μm or less.
Metal plate laminating molding characterized by containing up to 5% by weight
Polyester film for processing. R¹OC (O) XP (O) (OR²)₂  … (I) (Where R in the formula¹And R²Has 1 to 4 carbon atoms
Alkyl group, X is -CH₂-Or-CH (Y)-
(Y represents a benzene ring) and R¹And R ²Is
They may be the same or different. ) 2. The polyester is a copolyester containing a dicarboxylic acid component and a glycol component, the dicarboxylic acid component further contains terephthalic acid and isophthalic acid, and terephthalic acid is 82 mol% or more in all dicarboxylic acid components. At least 82 mol% of all glycol components is ethylene glycol.
A polyester film for forming and laminating a metal plate as described. 3. The polyester is a copolyester containing a dicarboxylic acid component and a glycol component, the dicarboxylic acid component further contains terephthalic acid and 2,6-naphthalenedicarboxylic acid, and terephthalic acid is contained in all dicarboxylic acid components. 82 mol% or more, and 82 mol% or more of all glycol components is ethylene glycol, The polyester film for metal plate laminating and forming according to claim 1, which is characterized in that. 4. The addition amount of the phosphorus compound and the titanium compound soluble in the polymer is in the range of the following formulas (1) to (3), wherein: Polyester film for metal plate laminating process. 2 ≦ Ti ≦ 10 (1) 0.1 ≦ P / Ti ≦ 10 (2) 5 ≦ Ti + P ≦ 40 (3) (In the above formula, Ti is contained in the polyester. The titanium element concentration (mmole%) of the polyester-soluble titanium compound and P the phosphorus element concentration (mmole%) of the phosphorus compound contained in the polyester, respectively.) 5. A polymer-soluble titanium compound is a compound represented by the following formula (II) or a compound represented by the following formula (I):
A metal plate sticking according to any one of claims 1 to 4, which is a product obtained by reacting a compound represented by I) with an aromatic polycarboxylic acid represented by the following formula (III). Polyester film for laminating process. Ti (OR ³ ) ₄ (II) (wherein R ³ in the formula (II) is an alkyl group or a phenyl group.) (Here, n in the formula (III) is an integer of 2 to 4.) 6. The polyester contains a glycol component, the glycol component further contains ethylene glycol and diethylene glycol, and ethylene glycol is 95 mol% or more in all glycol components. The polyester film for metal plate laminating and forming according to any one of 5 above. 7. The polyester film for metal plate laminating processing according to claim 1, wherein the melting point of the film is in the range of 210 to 250 ° C., and the glass transition point is 70 ° C. or higher. 8. The polyester film for laminating and processing metal plates according to claim 1, wherein the amount of film elution is 10 μg / cm ² or less.